Peonies are the royalty of the flower garden—graceful, long-lived, and utterly breathtaking when in full bloom.
They don’t ask for much: sunlight, well-drained soil, and a bit of space to stretch.
But what many gardeners don’t realize is that peonies can be quite particular about their neighbors.
Some plants seem harmless but can cause peonies to underperform, attract disease, or even stop blooming altogether.
Whether it’s due to crowding, moisture needs, or aggressive root systems, the wrong companions can be a silent threat to your peony patch.
If your peonies aren’t looking as full and fabulous as they should, take a close look at who they’re planted next to.
Here are five specific plants you should never grow near peonies—and exactly why they don’t make good garden friends.
Mint: A Bully in the Garden Bed
Mint might smell wonderful in a glass of lemonade or crushed into a summer dessert, but in the garden, it’s a different story.
This fast-growing herb may seem innocent at first, but it’s one of the worst things you can plant near your peonies.
Why?
Because mint is a garden bully.
It spreads rapidly through underground runners, taking over anything in its path.
Once mint gets comfortable, it doesn’t stay in its neat little patch—it creeps into neighboring spaces, including the territory your peonies need to grow.
Peonies don’t like competition.
They have deep roots and prefer space where they don’t have to battle other plants for nutrients or water.
When mint takes over, it competes aggressively for both.
This can stress your peonies, leaving them with smaller blooms, fewer stems, and slower growth.
The roots of mint can also tangle with peony roots, making it hard to dig one up without disturbing the other.
And unlike peonies, which stay in their place year after year, mint can pop up several feet from where you originally planted it.
If you’ve ever tried removing mint once it’s taken hold, you know how stubborn it is.
Even a small piece of root left behind can grow into a brand-new plant.
The only safe way to grow mint in a garden with peonies is in a container—and even then, keep that container far away.
If you’re tempted to tuck a few mint plants near your peonies for fragrance or groundcover, think twice.
It may seem harmless in year one, but by year two or three, your peonies will be suffering while the mint is thriving.
It’s better to give mint its own space where it can’t spread and leave your peonies in peace.
Hostas: Too Much Shade, Not Enough Breathing Room
Hostas are a shade gardener’s best friend.
With their lush foliage and low-maintenance attitude, it’s easy to see why so many people love planting them.
But while hostas are excellent in the right spot, that spot is not next to your peonies.
The first problem is light.
Peonies are sun lovers.
They need at least 6 hours of full sun each day to bloom their best.
Hostas, on the other hand, thrive in partial to full shade.
If you plant hostas nearby, you’re likely planting in a spot that doesn’t give your peonies enough light—or worse, the hostas will eventually grow large enough to block the light altogether.
When peonies don’t get enough sunlight, their blooms become fewer, smaller, and sometimes don’t appear at all.
But light isn’t the only issue here.
Hostas are space hogs.
They spread outward with thick, leafy growth that can crowd nearby plants and take over valuable garden real estate.
Peonies need room to breathe.
They don’t do well when their airflow is restricted or when other plants are too close.
Crowding can trap moisture around the stems and lead to fungal diseases, especially in wet or humid climates.
Hostas also prefer more moisture than peonies.
This difference in watering needs can create problems.
If you’re watering enough to keep your hostas happy, your peonies might be getting too much water—which they absolutely hate.
Too much moisture can lead to root rot and cause those gorgeous blooms to turn into mush before they even open.
So while both peonies and hostas are lovely on their own, they don’t make good neighbors.
If you love both plants, that’s totally fine—just don’t plant them side by side.
Keep your hostas in the shade garden and let your peonies soak up the sun in a spot with plenty of space and airflow.
They’ll thank you with a season full of breathtaking flowers.
Willow Trees: Water Hogs That Steal the Show
Willow trees are beautiful, graceful, and iconic in large landscapes—but they are absolutely terrible neighbors for peonies.
While a weeping willow swaying in the breeze might look peaceful, what’s happening underground is far from calm.
Willows have incredibly aggressive root systems that stretch far and wide in search of water.
These roots are thirsty, and they don’t care which plants they steal moisture from.
If you plant peonies anywhere near a willow tree, you’re setting them up for a losing battle.
Peonies have deep, tuberous roots, but they aren’t equipped to compete with the fast-moving, far-reaching roots of a willow.
As a result, they end up starved of water and nutrients.
Even if you’re watering your garden regularly, the willow will suck up most of that moisture before it ever reaches your peonies.
This can lead to weak stems, undersized buds, and very few flowers.
In some cases, your peonies may even fail to come up at all.
On top of the water competition, willows create a ton of shade as they grow.
Peonies, as you know, are sun worshippers—they need at least six hours of direct light each day.
If they’re stuck under the shadow of a willow, their growth will slow and bloom production will drop dramatically.
And because willow trees grow so quickly, they can overwhelm a garden space in just a few years.
If you already have a willow in your yard, give it plenty of distance from your flower beds—especially your peonies.
If you’re tempted to plant a willow tree near your garden for its ornamental appeal, consider a smaller, less aggressive tree instead.
Your peonies will thrive best when they’re planted far from these water-hogging giants.
Give them room, light, and moisture of their own, and they’ll reward you with unforgettable blooms.
Ferns: Moisture Lovers That Invite Trouble
Ferns bring texture and greenery to shady corners of the garden, and they’re favorites in woodland landscapes.
But despite their beauty, they’re not suitable companions for peonies.
In fact, planting ferns near your peonies could quietly sabotage your garden without you realizing it.
The main problem is moisture.
Ferns love damp soil.
They thrive in environments that are consistently moist, shady, and cool.
Peonies, on the other hand, prefer soil that’s well-draining and only lightly moist—too much water can cause major issues.
When you plant ferns near peonies, you often end up watering the area more than you should to keep the ferns happy.
This can lead to soggy soil that your peonies hate.
Too much moisture around the roots can cause fungal infections, crown rot, and a whole host of other issues.
Once rot sets in, it’s very difficult to stop—and your peony may not recover.
In addition to the water problem, ferns also create a lot of shade.
They may not grow as tall as trees, but when planted densely, they can block sunlight and reduce airflow around your peonies.
That trapped moisture, combined with poor air circulation, creates the perfect conditions for disease.
Peonies need space, sunlight, and a bit of dryness to really flourish.
Ferns unintentionally disrupt all three.
Even if your ferns are planted just a few feet away, they can still shift the moisture balance in the soil and create unfavorable conditions.
If you love ferns, there’s no reason to give them up—just keep them in a separate garden zone.
Plant them in shady, moist areas of your yard where they can thrive without putting your peonies at risk.
Your garden will be healthier, and your peonies will have the dry, sunny home they need to bloom their best.
Tomatoes: A Risky Mix of Disease and Competition
Tomatoes and peonies might both be garden favorites, but they do not make good neighbors.
In fact, planting them close together is a recipe for frustration.
Tomatoes belong to the nightshade family, a group of plants that are prone to a wide range of diseases—many of which can spread easily to nearby plants, including your precious peonies.
One of the biggest threats is botrytis blight, a fungal disease that thrives in moist conditions and affects both tomatoes and peonies.
If your tomatoes catch it, your peonies are likely next.
This disease causes buds to rot, stems to turn black, and flowers to wilt before they open.
And once it’s in your soil, it can linger and cause problems for years to come.
Tomatoes also attract aphids and whiteflies, pests that may not target peonies directly but can still create a stressful environment in your flower bed.
These pests suck sap from nearby plants and can spread viruses as they move from one host to another.
Beyond the disease risk, tomatoes and peonies have very different growth habits and care needs.
Tomatoes are fast-growing, sprawling plants that demand constant feeding and frequent watering.
They need rich, moist soil, regular pruning, and often a fair amount of space to stretch out and climb.
Peonies, on the other hand, prefer less water, simpler care, and more room for air circulation.
When planted too close to tomatoes, peonies may end up fighting for light, nutrients, and space.
This can lead to poor blooming, stressed plants, and a general decline in health.
So while it might be convenient to mix your flowers and veggies in one spot, it’s best to keep tomatoes far away from peonies.
Your peonies will be much happier—and much healthier—without tomatoes crowding the garden bed.
Final Thoughts
Peonies are strong, dependable, and incredibly beautiful, but they need the right environment to truly shine.
Planting them near aggressive spreaders, shade lovers, water hogs, or disease-prone plants can lead to disappointment.
Choosing the wrong neighbors can crowd your peonies, dry them out, drown them in moisture, or introduce harmful pests and fungi.
By keeping mint, hostas, willow trees, ferns, and tomatoes out of their space, you’re giving your peonies exactly what they crave: sun, airflow, well-drained soil, and peace.
With the right companions—or no companions at all—your peonies will reward you with season after season of breathtaking blooms.
In the garden, who you grow next to matters.
Let your peonies have the room and respect they deserve, and they’ll always put on a show.